In the manufacturing process of a semiconductor integrated circuit (IC), a desired pattern (shape) is transferred to a resist film by exposing the resist film formed on a semiconductor substrate.
One method for exposing the resist film is an electron beam exposure method. As the electron beam exposure method, variable shaped beam (hereafter referred to as VSB) lithography is well known, in which patterns are transferred one by one by variable shaped beams. However, the VSB method has a problem of low throughput because of a large number of exposure times.
To solve the above problem, a character projection (hereafter referred to as CP) method has been developed. In the CP method, the aperture shape of a block mask (hereafter referred to as block mask pattern) is transferred to the resist film by irradiating the resist film with an electron beam through the block mask. Thus, the throughput is improved because patterns in a prescribed area (for example, a rectangular area having each side of 1 μm) are formed collectively at one-time electron beam exposure.